US7688544B1 - Magnetic heads disk drives and methods with floating pole tip or shunted pole tip for reduced pole tip erasure - Google Patents
Magnetic heads disk drives and methods with floating pole tip or shunted pole tip for reduced pole tip erasure Download PDFInfo
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- US7688544B1 US7688544B1 US11/438,452 US43845206A US7688544B1 US 7688544 B1 US7688544 B1 US 7688544B1 US 43845206 A US43845206 A US 43845206A US 7688544 B1 US7688544 B1 US 7688544B1
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- pole tip
- yoke
- head
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- G—PHYSICS
- G08—SIGNALLING
- G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
- G08B13/00—Burglar, theft or intruder alarms
- G08B13/18—Actuation by interference with heat, light, or radiation of shorter wavelength; Actuation by intruding sources of heat, light, or radiation of shorter wavelength
- G08B13/189—Actuation by interference with heat, light, or radiation of shorter wavelength; Actuation by intruding sources of heat, light, or radiation of shorter wavelength using passive radiation detection systems
- G08B13/194—Actuation by interference with heat, light, or radiation of shorter wavelength; Actuation by intruding sources of heat, light, or radiation of shorter wavelength using passive radiation detection systems using image scanning and comparing systems
- G08B13/196—Actuation by interference with heat, light, or radiation of shorter wavelength; Actuation by intruding sources of heat, light, or radiation of shorter wavelength using passive radiation detection systems using image scanning and comparing systems using television cameras
- G08B13/19678—User interface
- G08B13/19691—Signalling events for better perception by user, e.g. indicating alarms by making display brighter, adding text, creating a sound
- G08B13/19693—Signalling events for better perception by user, e.g. indicating alarms by making display brighter, adding text, creating a sound using multiple video sources viewed on a single or compound screen
-
- G—PHYSICS
- G08—SIGNALLING
- G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
- G08B13/00—Burglar, theft or intruder alarms
- G08B13/18—Actuation by interference with heat, light, or radiation of shorter wavelength; Actuation by intruding sources of heat, light, or radiation of shorter wavelength
- G08B13/189—Actuation by interference with heat, light, or radiation of shorter wavelength; Actuation by intruding sources of heat, light, or radiation of shorter wavelength using passive radiation detection systems
- G08B13/194—Actuation by interference with heat, light, or radiation of shorter wavelength; Actuation by intruding sources of heat, light, or radiation of shorter wavelength using passive radiation detection systems using image scanning and comparing systems
- G08B13/196—Actuation by interference with heat, light, or radiation of shorter wavelength; Actuation by intruding sources of heat, light, or radiation of shorter wavelength using passive radiation detection systems using image scanning and comparing systems using television cameras
- G08B13/19617—Surveillance camera constructional details
- G08B13/19632—Camera support structures, e.g. attachment means, poles
-
- G—PHYSICS
- G08—SIGNALLING
- G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
- G08B13/00—Burglar, theft or intruder alarms
- G08B13/18—Actuation by interference with heat, light, or radiation of shorter wavelength; Actuation by intruding sources of heat, light, or radiation of shorter wavelength
- G08B13/189—Actuation by interference with heat, light, or radiation of shorter wavelength; Actuation by intruding sources of heat, light, or radiation of shorter wavelength using passive radiation detection systems
- G08B13/194—Actuation by interference with heat, light, or radiation of shorter wavelength; Actuation by intruding sources of heat, light, or radiation of shorter wavelength using passive radiation detection systems using image scanning and comparing systems
- G08B13/196—Actuation by interference with heat, light, or radiation of shorter wavelength; Actuation by intruding sources of heat, light, or radiation of shorter wavelength using passive radiation detection systems using image scanning and comparing systems using television cameras
- G08B13/19634—Electrical details of the system, e.g. component blocks for carrying out specific functions
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- G—PHYSICS
- G08—SIGNALLING
- G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
- G08B13/00—Burglar, theft or intruder alarms
- G08B13/18—Actuation by interference with heat, light, or radiation of shorter wavelength; Actuation by intruding sources of heat, light, or radiation of shorter wavelength
- G08B13/189—Actuation by interference with heat, light, or radiation of shorter wavelength; Actuation by intruding sources of heat, light, or radiation of shorter wavelength using passive radiation detection systems
- G08B13/194—Actuation by interference with heat, light, or radiation of shorter wavelength; Actuation by intruding sources of heat, light, or radiation of shorter wavelength using passive radiation detection systems using image scanning and comparing systems
- G08B13/196—Actuation by interference with heat, light, or radiation of shorter wavelength; Actuation by intruding sources of heat, light, or radiation of shorter wavelength using passive radiation detection systems using image scanning and comparing systems using television cameras
- G08B13/19639—Details of the system layout
- G08B13/19641—Multiple cameras having overlapping views on a single scene
- G08B13/19643—Multiple cameras having overlapping views on a single scene wherein the cameras play different roles, e.g. different resolution, different camera type, master-slave camera
-
- G—PHYSICS
- G08—SIGNALLING
- G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
- G08B25/00—Alarm systems in which the location of the alarm condition is signalled to a central station, e.g. fire or police telegraphic systems
- G08B25/009—Signalling of the alarm condition to a substation whose identity is signalled to a central station, e.g. relaying alarm signals in order to extend communication range
Definitions
- the present invention relates generally to disk drive write heads with pole tips that have reduced pole-tip erasure properties, and to methods of manufacturing such write heads.
- Disk drives are used in a wide variety of electronic devices, ranging from personal computers to portable media players, for the storage and retrieval of data.
- data is typically written to and read from magnetic storage media called disks.
- a disk drive typically comprises a plurality of disks for the storage of data and one or more read/write heads for the reading and writing of data.
- longitudinal recording has been used to record data on a disk drive.
- the data bits are aligned parallel to the surface of the disk.
- Each bit is composed of a group of magnetic grains with magnetization aligned parallel to the disk surface; in a write operation, the write head flips the magnetization of the grains for each bit horizontally, parallel to the surface of the disk.
- the write head typically comprises a pole tip, a yoke supporting the pole tip, and a conductive coil surrounding the yoke for electrically magnetizing the pole tip.
- the write head is moved to the location of the bit of data such that the pole tip is positioned directly above the bit, an electric current is passed through the coils to magnetize the pole tip, which in turn causes the magnetization of the bit to change.
- perpendicular recording has been introduced to achieve greater data storage density for disk drives.
- the magnetization of each bit is aligned vertically, perpendicular to the disk surface.
- the write head flips the magnetization of the grains for each bit vertically, with either the north pole close to the surface or away from the surface.
- the perpendicular recording system allows more data bits per unit of disk surface area, which in turn enables greater data storage density for the disk drives.
- a perpendicular recording system uses less disk surface area for each bit of data compared to a comparable longitudinal recording system. With the decease of surface area per bit of data, the dimensions of the pole tip of the write head must be reduced as well.
- a problem occurs when the magnetic state of the pole tip does not return to zero magnetization when the current in the conductive coils of the write head is stopped. This causes the pole tip to maintain some remnant magnetization field; and, as the write head moves across the disk, the pole tip can inadvertently change the magnetization state of other bits on the disk. This phenomenon is commonly known as pole tip erasure (PE) or pole tip lockup. Pole tip erasure (PE) can corrupt the data stored on the disk, and cause catastrophic failure for the disk drive.
- PE pole tip erasure
- PE Pole tip erasure
- pole tip erasure PE
- pole tip lockup There are several potential causes for the presence of remnant magnetic fields that cause pole tip erasure (PE) or pole tip lockup.
- PE pole tip erasure
- One possible cause is the shape anisotropy of the pole tip. As the dimensions of the write pole tip decrease, the write pole tip becomes more similar in shape to a long-thin needle.
- the transverse self-demagnetizing field of the needle-like shape of the pole tip could potentially cause the magnetic domains of the pole tip to form into a lengthwise remnant magnetic state. That is, the magnetostatic energy is less when the magnetization is in the long axis of the needle compared to the short axis.
- domain lockup of the yoke Another possible cause of remnant magnetization in the pole tip is domain lockup of the yoke.
- the magnetization of the yoke may not immediately return to a zero-magnetization state after the current in the conductive coils is stopped; this in turn causes the pole tip to remain magnetized.
- a domain structure of the yoke with predominantly transverse magnetization will minimize domain lockup of the yoke.
- a domain structure with predominantly axial magnetization will enhance lockup of the yoke.
- Undesirable domain structures may be caused by axial magnetostriction anisotropy due to the interaction of the anisotropic stress field of the yoke with the magnetostriction of the yoke alloy.
- the lamination method proposed by Bai and Zhu requires the insertion of a very thin (7 ⁇ ) layer in the middle of the deposition of the write yoke and write pole tip. Such a process step is expensive, time-consuming, difficult to control, and incompatible with electroplating manufacturing processes.
- Embodiments of the present invention relate generally to disk drive write heads with designs that minimize the effects of pole-tip erasure caused by remnant magnetic fields in the write yoke or the write pole tip.
- a disk drive comprises a write shield, a write return yoke connected to the write shield, a write yoke connected to the write return yoke, conductive coils surrounding the write yoke, a write pole tip, and a spacer connecting the write pole tip to the write yoke.
- the conductive coils surrounding the write yoke induce a magnetic field in the write yoke when an electric current passes through the conductive coils.
- the spacer connecting the write pole tip and the write yoke prevents a magnetization of the write pole tip when there is a small remnant magnetic field in the write yoke.
- the spacer is composed of a non-magnetic material. Hence, in such embodiments, the spacer acts as a non-magnetic gap between the magnetic write pole tip and write yoke.
- the write shield, the write yoke, the write return yoke and the write pole tip are each composed of a soft ferromagnetic material.
- the material for the spacer is thermally conductive. In some embodiments, the spacer is composed of copper.
- the spacer is dimensioned such that the magnetic impedance between the pole tip and the write yoke is greater than 35% of the magnetic impedance between the pole tip and a soft underlayer of a disk of the disk drive, when the write head is positioned above the disk during a write operation.
- the spacer is oriented substantially perpendicular to an air-bearing-surface (ABS) of a disk of the disk drive when the write head is positioned above the disk during a write operation.
- ABS air-bearing-surface
- the spacer is oriented substantially parallel to the length direction of the write pole tip.
- a write head for a disk drive comprises a write shield, a write return yoke connected to the write shield, a write yoke connected to the write return yoke, conductive coils surrounding the write yoke for inducing a magnetic field in the write yoke, a write pole tip, and a shunt connecting the write pole tip to the write shield for providing a magnetic flux path between the write pole tip and the write shield.
- the shunt is composed of a low saturation magnetization (Ms) material.
- Ms low saturation magnetization
- the shunt is capable of directing a limited amount of magnetic flux such that when the pole tip is at a low magnetization state, all magnetic flux from the pole tip is directed to the write shield via the shunt; and, when the pole tip is at a high magnetization state, the shunt becomes saturated and only a fixed amount of magnetic flux is directed from the pole tip to the write shield.
- the remnant magnetization is directed to the write shield via the shunt.
- the magnetization in the write pole tip is high due to the magnetization caused by the conducting coils during a write operation, the shunt is saturated and most of the magnetic flux is directed from the write pole tip to the disk.
- the shunt is oriented substantially perpendicular to an air-bearing-surface (ABS) of a disk when the write head is positioned above the disk during a write operation. In other various embodiments, the shunt is oriented substantially parallel to the ABS during a write operation.
- ABS air-bearing-surface
- a method for manufacturing a write head comprises providing a first layer, depositing a write pole tip on a first portion of the first layer, depositing a first insulating layer on a second portion of the first layer, depositing a spacer layer on a first portion of the write pole tip, depositing a second insulating layer on a second portion of the write pole tip, depositing a write yoke on at least a portion of the spacer layer and on at least a portion of the first insulating layer, depositing a write shield on a portion of the second insulating layer, and depositing a write return yoke on at least a portion of the write yoke and on at least a portion of the write shield.
- the method for manufacturing the write head further comprises the formation of a read head.
- the method for manufacturing a write head further comprises the steps of depositing a seed layer after the step of deposition of the spacer layer, and defining said seed layer to form a shunt.
- the method for manufacturing a write head further comprises the step of etching a hole in the second insulating layer connecting the pole tip and the write shield, and filling the hole with a low magnetization material for the formation of a shunt between the pole tip and the write shield.
- a disk drive device comprises at least one magnetic recording medium, and at least one magnetic head supported for perpendicular recording on the at least one magnetic recording medium.
- each magnetic head may comprise a write shield, a write return yoke connected to the write shield, a write yoke connected to the write return yoke, conductive coils surrounding the write yoke for inducing a magnetic field in the write yoke, a write pole tip, and a spacer connecting the write pole tip to the write yoke.
- the magnetic head of the disk drive device further comprises a shunt connecting the write pole tip and the write shield for providing a magnetic flux path between the write pole tip and the write shield.
- a disk drive device comprises at least one magnetic recording medium, and at least one magnetic head supported for perpendicular recording on the at least one magnetic recording medium.
- each magnetic head may comprise a write shield, a write return yoke connected to the write shield, a write yoke connected to the write return yoke, conductive coils surrounding the write yoke for inducing a magnetic field in the write yoke, a write pole tip, and a shunt connecting the write pole tip and the write shield for providing a magnetic flux path between the write pole tip and the write shield.
- FIG. 1 illustrates a simplified top view of a disk drive
- FIG. 2 illustrates a prior art design of a read/write head
- FIG. 3 illustrates a write head with a non-magnetic spacer according to an embodiment of the present invention
- FIG. 4 illustrates a cross-sectional view of a manufacturing process for manufacturing a write head with a non-magnetic spacer in accordance with an embodiment of the present invention
- FIG. 5 illustrates a write head with a non-magnetic spacer according to an embodiment of the present invention
- FIG. 6 illustrates a write head with a saturable yoke shunt according to an embodiment of the present invention
- FIG. 7 illustrates a write head with a non-magnetic spacer and a saturable yoke shunt according to yet another embodiment of the present invention
- FIG. 8 illustrates a cross-sectional view of a manufacturing process for manufacturing a write head with a saturable yoke shunt that is oriented substantially perpendicular to an air-bearing-surface (ABS) in accordance with an embodiment of the present invention
- FIG. 9 illustrates a cross-sectional view of a manufacturing process for manufacturing a write head with a saturable yoke shunt that is oriented substantially parallel to an air-bearing-surface (ABS) in accordance with an embodiment of the present invention
- FIG. 10 illustrates a write head with a saturable yoke shunt according to an embodiment of the present invention.
- FIG. 11 illustrates simulated performance results of a write head with a non-magnetic spacer (line labeled “GAP 2 ”), a write head with a saturable yoke shunt (line labeled “Short”), compared to a performance of a prior art write head design (line labeled “Original”), where the x-axis represents a current through magnetic coils, and the y-axis represents a resulting magnetic field in the write pole tip.
- GAP 2 non-magnetic spacer
- Short saturable yoke shunt
- the present invention relates to write head designs which utilizes a non-magnetic spacer or a saturable magnetic shunt to reduce or eliminate the effects of remnant magnetic fields which cause pole tip erasures (PE).
- PE pole tip erasures
- FIG. 1 illustrates one embodiment of a disk drive 10 .
- the disk drive 10 generally includes a base plate 12 and a cover (not shown) that may be disposed on the base plate 12 to define an enclosed housing or space for the various disk drive components.
- the disk drive 10 includes one or more data storage disks 14 of any appropriate computer-readable data storage media. Typically, both of the major surfaces of each data storage disk 14 include a plurality of concentrically disposed tracks for data storage purposes.
- Each disk 14 is mounted on a hub or spindle 16 , which in turn is rotatably interconnected with the disk drive base plate 12 and/or cover. Multiple data storage disks 14 are typically mounted in vertically spaced and parallel relation on the spindle 16 . Rotation of the disk(s) 14 is provided by a spindle motor 18 that is coupled to the spindle 16 to simultaneously spin the data storage disk(s) 14 at an appropriate rate.
- the disk drive 10 also includes an actuator arm assembly 20 that pivots about a pivot bearing 22 , which in turn is rotatably supported by the base plate 12 and/or cover.
- the actuator arm assembly 20 includes one or more individual rigid actuator arms 24 that extend out from near the pivot bearing 22 .
- Multiple actuator arms 24 are typically disposed in vertically spaced relation, with one actuator arm 24 being provided for each major data storage surface of each data storage disk 14 of the disk drive 10 .
- Other types of actuator arm assembly configurations could be utilized as well, such as an “E” block having one or more rigid actuator arm tips or the like that cantilever from a common structure.
- movement of the actuator arm assembly 20 is provided by an actuator arm drive assembly, such as a voice coil motor 26 or the like.
- the voice coil motor 26 is a magnetic assembly that controls the operation of the actuator arm assembly 20 under the direction of control electronics 28 .
- Any appropriate actuator arm assembly drive type may be utilized by the disk drive 10 , including a linear drive (for the case where the actuator arm assembly 20 is interconnected with the base plate 12 and/or cover for linear movement versus the illustrated pivoting movement about the pivot bearing 22 ) and other types of rotational drives.
- a load beam or suspension 30 is attached to the free end of each actuator arm 24 and cantilevers therefrom. Typically, the suspension 30 is biased generally toward its corresponding disk 14 by a spring-like force.
- a slider 32 is disposed at or near the free end of each suspension 30 . What is commonly referred to as the “head” (e.g., transducer) is appropriately mounted on the slider 32 and is used in disk drive read/write operations.
- the head on the slider 32 may utilize various types of read sensor technologies such as anisotropic magnetoresistive (AMR), giant magnetoresistive (GMR), tunneling magnetoresistive (TuMR), other magnetoresistive technologies, or other suitable technologies.
- AMR is due to the anisotropic magnetoresistive effect with a normalized change in resistance (AR/R) of 2-4%.
- GMR results from spin-dependent scattering mechanisms between two (or more) magnetic layers.
- the typical use in recording heads is the spin valve device that uses a pinned magnetic layer and a free layer to detect external fields.
- the normalized change in resistance is typically 8-12%, but can be as large as 15-20% when used with specular capping layers and spin-filter layers.
- TuMR is similar to GMR, but is due to spin dependent tunneling currents across an isolation layer.
- the typical embodiment includes a free layer and a pinned layer separated by a insulating layer of Al 2 O 3 with the current flowing perpendicular to the film plane, producing normalized change in resistance of 12-25%.
- magnetoresistive is used in this application to refer to all these types of magnetoresistive sensors and any others in which a variation in resistance of the sensor due to the application of an external magnetic field is detected.
- the write transducer technology of the head of the present invention is discussed in further detail below.
- biasing forces exerted by the suspension 30 on its corresponding slider 32 thereby attempt to move the slider 32 in the direction of its corresponding disk 14 .
- this biasing force is such that if the slider 32 were positioned over its corresponding disk 14 , without the disk 14 being rotated at a sufficient velocity, the slider 32 would be in contact with the disk 14 .
- the head on the slider 32 is interconnected with the control electronics 28 of the disk drive 10 by a flex cable 34 that is typically mounted on the actuator arm assembly 20 . Signals are exchanged between the head and its corresponding data storage disk 14 for disk drive read/write operations.
- the voice coil motor 26 is utilized to pivot the actuator arm assembly 20 to simultaneously move the slider 32 along a path 36 and “across” the corresponding data storage disk 14 to position the head at the desired/required radial position on the disk 14 (i.e., at the approximate location of the correct track on the data storage disk 14 ) for disk drive read/write operations.
- the actuator arm assembly 20 When the disk drive 10 is not in operation, the actuator arm assembly 20 is pivoted to a “parked position” to dispose each slider 32 generally at or beyond a perimeter of its corresponding data storage disk 14 , but in any case in vertically spaced relation to its corresponding disk 14 .
- This is commonly referred to in the art as being a dynamic load/unload disk drive configuration.
- the disk drive 10 includes a ramp assembly 38 that is disposed beyond a perimeter of the data storage disk 14 to typically both move the corresponding slider 32 vertically away from its corresponding data storage disk 14 and to also exert somewhat of a retaining force on the actuator arm assembly 20 . Any configuration for the ramp assembly 38 that provides the desired “parking” function may be utilized.
- the disk drive 10 could also be configured to be of the contact start/stop type, where the actuator arm assembly 20 would pivot in a direction to dispose the slider(s) 32 typically toward an inner, non-data storage region of the corresponding data storage disk 14 . Terminating the rotation of the data storage disk(s) 14 in this type of disk drive configuration would then result in the slider(s) 32 actually establishing contact with or “landing” on its corresponding data storage disk 14 , and the slider 32 would remain on the disk 14 until disk drive operations are re-initiated.
- the slider 32 of the disk drive 10 may be configured to “fly” on an air bearing during rotation of its corresponding data storage disk(s) 14 at a sufficient velocity.
- the slider 32 may be disposed at a pitch angle such that its leading edge is disposed further from its corresponding data storage disk 14 than its trailing edge.
- the head would typically be incorporated on the slider 32 generally toward its trailing edge since this is positioned closest to its corresponding disk 14 .
- Other pitch angles/orientations could also be utilized for flying the slider 32 .
- FIG. 2 illustrates a typical prior art design of a head 33 that may be mounted on a slider 32 (refer to FIG. 1 ).
- the head 33 comprises a read head 40 and a write head 50 .
- the read head 40 typically comprises a read sensor 41 , and read shields 44 and 45 .
- the write head 50 typically comprises a pole tip 51 , a write yoke 56 , a write return yoke 55 , and a write shield 53 .
- the write head 50 comprises conductive coils 58 surrounding the write yoke 56 for the generation of a magnetic field. When an electric current is passed through the conductive coils 58 , the current generates a magnetic field in the write yoke 56 , which causes the pole tip 51 to become magnetized.
- FIG. 1 illustrates a typical prior art design of a head 33 that may be mounted on a slider 32 (refer to FIG. 1 ).
- the head 33 comprises a read head 40 and a write head 50 .
- the disk 14 comprises a soft underlayer (SUL) 141 supporting a magnetic storage layer 143 , where the SUL 141 and the storage layer 143 may be separated in various embodiments by a non-magnetic spacer layer (not shown).
- SUL soft underlayer
- the conductive coils 58 are composed of a material with low electrical resistance, such as copper, or the like.
- the pole tip 51 , write yoke 56 , write return yoke 55 , and write shield 53 are all composed of soft ferromagnetic materials, such as NiFe, or the like, and are all magnetically connected to each other. (The term “soft” describes the magnetic, not physical, property of the material.) Hence, in the situation where there is a remnant magnetic field in the write yoke 56 , the pole tip 51 would also become magnetized.
- the slider 32 moves to a position where the head 33 is positioned directly above the region of the disk 14 corresponding to a bit of data, where the write head 50 and the disk 14 are separated by an air-bearing.
- a current flows through the conductive coils 58 of the write head 50 generating a magnetic field in the write yoke 56 .
- the magnetization in the write yoke 56 causes the pole tip 51 to become magnetized.
- the SUL 141 is typically composed of a magnetically soft material with higher magnetic permeability compared to the material of the magnetic storage layer 143 .
- the magnetic flux 80 from the pole tip 51 passes vertically through the magnetic storage layer 143 to the SUL 141 .
- the magnetic flux 80 then passes through the SUL 141 and returns to the write return yoke 55 (return path).
- the tip area of the pole tip 51 is small, the magnetic flux 80 density is high in the region of the magnetic storage layer 143 positioned immediately under the pole tip 51 ; hence, the magnetic flux 80 is capable of causing a change of the storage state of a bit of data.
- the write return yoke 55 is wider in surface area, the magnetic flux density on the return path is lower since it is distributed over a wider area, therefore the storage state of the magnetic storage layer 143 on the return path remains unchanged.
- FIG. 3 illustrates an embodiment of the present invention where a non-magnetic spacer 52 is inserted between the pole tip 51 and the write yoke 56 .
- the non-magnetic spacer 52 is composed of a non-magnetic material.
- the material for the non-magnetic spacer 52 should also have good thermal conductivity.
- One possible material is copper; however, other materials that meet the criteria discussed above can also be used.
- Suitable materials for the non-magnetic spacer 52 further include alumina (Al 2 O 3 ), non-magnetic nickel-phosphorous, gold, tantalum, tantalum-oxide, and the like.
- the pole tip 51 is magnetically separated from the write yoke 56 by the non-magnetic spacer 52 .
- the pole tip 51 is magnetically separated from the write yoke 56 by the non-magnetic spacer 52 .
- the thickness of the non-magnetic spacer 52 is relatively thin, when the magnetization in the write yoke 56 is high from a current flowing through the conductive coils 58 , the magnetic field of the write yoke 56 could overcome the magnetic impedance of the non-magnetic spacer 52 , and the write yoke 56 could still magnetize the pole tip 51 . Therefore, the structure illustrated in FIG. 3 is less likely to cause pole tip erasure when there is no current in the conductive coils 58 because the non-magnetic spacer 52 prevents the pole tip 51 from getting magnetized by remnant magnetic fields from the write yoke 56 , while still allowing for performing write operations when the write yoke 56 is highly magnetized.
- FIG. 11 illustrates the simulation result of the magnetic field (shown on the y-axis) of the pole tip 51 in a conventional design (diamond line labeled “Original”) compared with a design with a non-magnetic spacer 52 (square line labeled “GAP 2 ”).
- the graph illustrates, at low currents (shown on the x-axis) representing a remnant magnetic field in the write yoke 56 or in the pole tip 51 , the magnetic field of the pole tip with a non-magnetic spacer 52 could be more than 50% reduced from that of the conventional design. However, at high currents, the magnetic field of the pole tip remains close to that of the conventional design, with little efficiency loss. It is noted that the simulation results shown in FIG.
- the impedance between the SUL 141 and the write pole tip 51 can be approximated by: Impedance of Pole Tip to SUL ⁇ (Tip to SUL distance)/(Tip Area on ABS)
- the impedance between the tip and the yoke can be approximated by: Impedance of Tip to Yoke ⁇ (Thickness of non-magnetic spacer)/(overlapping area of non-magnetic spacer)
- the perpendicular spacer design shown in FIG. 3 enables a write head design such that the magnetic impedance between the pole tip 51 and the write yoke 56 is greater than 35% of the magnetic impedance between the pole tip 51 and the SUL 141 .
- FIG. 4 is oriented such that the air-bearing surface (ABS) 60 is on the right side of the illustration.
- ABS air-bearing surface
- a substrate 81 is provided.
- the substrate 81 may comprise, for example, AlTiC, or the like.
- An undercoat layer 82 is deposited on the substrate 81 .
- the undercoat layer 82 may comprise, for example, Al 2 O 3 , or the like.
- a first read shield 45 is deposited on the undercoat layer 82 .
- the first read shield 45 may comprise, for example, a ferromagnetic material, such as NiFe, or the like.
- a first portion of a first insulating layer 84 is deposited on the first read shield 45 .
- the first insulating layer 84 may comprise, for example, Al 2 O 3 , or the like.
- the read sensor 41 is deposited on the first portion of the first insulating layer 84 and a remainder of the first insulating layer 84 is deposited over the read sensor 41 .
- a second read shield 44 is deposited on the first insulating layer 84 .
- the second read shield 44 may comprise, for example, a ferromagnetic material, such as NiFe, or the like.
- a third insulating layer 86 is deposited on the second read shield 44 .
- the second insulating layer 86 may comprise, for example, Al 2 O 3 , or the like.
- the second insulating layer 86 may act as a first layer for the write head 50 (refer to FIG. 3 ).
- the write pole tip 51 is deposited on a first portion of the second insulating layer 86 .
- a third insulating layer 79 is deposited on a second portion of the second insulating layer 86 .
- the third insulating layer 79 may comprise, for example, Al 2 O 3 , or the like.
- the non-magnetic spacer 52 is deposited on a first portion of the write pole tip 51 .
- a first portion of the write yoke 56 is deposited on at least a portion of the non-magnetic spacer 52 and on at least a portion of the third insulating layer 79 .
- a fourth insulating layer 77 is deposited on a portion of the write pole tip 51 and on a portion of the write yoke 56 and on a portion of the third insulating layer 79 .
- the fourth insulating layer 77 may comprise, for example, Al 2 O 3 , or the like.
- a photoresist layer 76 with an arrangement of the conductive coils 58 is deposited on the fourth insulating layer 77 .
- a fifth insulating layer 78 is deposited on the photoresist layer 76 .
- the fifth insulating layer 78 may comprise, for example, Al 2 O 3 , or the like.
- a first etching process removes a first portion of the fifth insulating layer 78 , a first portion of the photoresist layer 76 , and a first portion of the fourth insulating layer 77 , exposing a particular portion of the write yoke 56 .
- a remaining portion of the write yoke 56 is then deposited on the particular portion of the write yoke 56 in the area that was defined by the first etching process. Also, a second etching process removes a second portion of the fifth insulating layer 78 , a second portion of the photoresist layer 76 , and a second portion of the fourth insulating layer 77 .
- the write shield 53 is deposited on a particular portion of the fourth insulating layer 77 in the area defined by the second etching process.
- the write return yoke 55 is deposited on a portion of the write yoke 56 and on a portion of the write shield 53 and on a portion of the fifth insulating layer 78 .
- an overcoat layer 88 is deposited on a portion of the fifth insulating layer 78 and on the write return yoke 55 .
- the overcoat layer 88 may comprise, for example, Al 2 O 3 , or the like.
- the resulting structure is a write head 50 with a non-magnetic spacer 52 between the pole tip 51 and the write yoke 56 , manufactured using a conventional manufacturing process.
- the non-magnetic spacer 52 is deposited parallel to the substrate 81 in the manufacturing process (and thus perpendicular to the ABS 60 ), a thickness of the non-magnetic spacer 52 can be easily controlled in the manufacturing process.
- the write head 50 and the read head 40 are typically manufactured together on the same substrate. The manufacturing process described above is compatible with such an arrangement. In various other embodiments, the read head 40 and the write head 50 may be manufactured separately.
- FIG. 5 illustrates the disk 14 and the write head 50 with the non-magnetic spacer 52 in accordance with another embodiment of the present invention.
- the write head 50 of FIG. 5 differs from the write head 50 of FIG. 3 in that the non-magnetic spacer 52 in the write head 50 of FIG. 5 is located at least partially between a portion of the write yoke 56 and a portion of the write return yoke 55 . Also, at least a portion of the write pole tip 51 in the write head 50 of FIG. 5 is located at least partially between a portion of the non-magnetic spacer 52 and a portion of the write return yoke 55 .
- a gap 90 between the write pole tip 51 and the write shield 53 may be set to different distances. Also, in some embodiments, the write shield 53 may be omitted from the write head 50 .
- FIGS. 6-10 illustrate various other embodiments of the present invention in which pole tip erasure is reduced using a saturable yoke shunt 57 .
- FIG. 6 illustrates a write head 50 according to an embodiment of the present invention.
- the write head 50 comprises a write pole tip 51 , write yoke 56 , write return yoke 55 , write shield 53 , conductive coils 58 , and a saturable yoke shunt 57 connecting the pole tip 51 and the write shield 53 .
- the material for the saturable yoke shunt 57 is preferably a material with low saturation magnetization (Ms), such as Ni—P, or the like.
- Ms low saturation magnetization
- the saturable yoke shunt 57 provides a path for directing a limited amount of magnetic flux from the pole tip 51 to the return path (the write shield 53 ). In cases where the pole tip 51 remains magnetized with a remnant field, the magnetic flux is shunted to the write shield 53 , instead of being passed to the disk 14 to cause pole tip erasure (PE). However, while the write head 50 is in operation and there is a current flowing through the conductive coils 58 causing a strong magnetic field in the pole tip 51 , the saturable yoke shunt 57 becomes saturated such that only a limited amount of magnetic flux can be shunted to the write shield 53 , and the majority of the magnetic flux passes to the disk 14 to achieve the desired write operation.
- PE pole tip erasure
- FIG. 11 compares the magnetic field (shown on the y-axis) of a pole tip 51 in a conventional design (diamond line labeled “Original”) and a pole tip 51 with a saturable yoke shunt 57 (triangle line labeled “Short”).
- the magnetic field of the pole tip 51 is reduced by more than 50% when using a saturable yoke shunt 57 compared to a conventional design.
- the shunt becomes saturated such the efficiency loss associated with the use of the shunt 57 is relatively small.
- FIG. 7 illustrates yet another embodiment of the present invention.
- the write head 50 illustrated in FIG. 7 comprises both a non-magnetic spacer 52 and a saturable yoke shunt 57 .
- the pole tip 51 enjoys protection against pole tip erasure from both the non-magnetic spacer 52 and the saturable yoke shunt 57 .
- FIGS. 8 and 9 illustrate two possible methods of manufacturing the saturable yoke shunt 57 .
- the air-bearing-surface (ABS) 60 is on the right edge of the illustrations.
- FIG. 8 illustrates one embodiment of the present invention in which the saturable yoke shunt 57 is manufactured substantially perpendicular to the ABS 60 , and substantially parallel to the substrate 81 .
- the write pole tip 51 is deposited and encapsulated with Al 2 O 3 , or the like, and then is planarized with a chemo-mechanical lapping (CMP).
- CMP chemo-mechanical lapping
- a portion of the fourth insulating layer 77 is deposited, a magnetic seed for the write yoke 56 is deposited, and the write yoke 56 is platted. Then, the seed is masked in a shunt region and is ion milled to leave the saturable yoke shunt 57 . Finally, the rest of the structure is completed (coils and write shield deposition) as explained above with reference to FIG. 4 .
- FIG. 9 illustrates another embodiment of the present invention in which the saturable yoke shunt 57 is manufactured substantially parallel to the ABS 60 , and substantially perpendicular to the substrate 81 .
- a photolithography step is utilized to expose an opening in the portion of the fourth insulating layer 77 .
- the material in the fourth insulating layer 77 defined by the opening is then removed using an etch step or an ion milling step to form a pin-hole.
- the pin-hole is then filled with a low saturation magnetization (Ms) material, so as to create the saturable yoke shunt 57 .
- Ms low saturation magnetization
- FIG. 10 illustrates yet another embodiment of the present invention in which the write head 50 does not have a write shield 53 and the saturable yoke shunt connects the pole tip 51 and the write return yoke 55 .
Abstract
Description
Impedance of Pole Tip to SUL˜(Tip to SUL distance)/(Tip Area on ABS)
Impedance of Tip to Yoke˜(Thickness of non-magnetic spacer)/(overlapping area of non-magnetic spacer)
Fractional Reduction in Erasure Field=x/(1+x), where x=(thickness of non-magnetic spacer*Tip Area on ABS)/(Tip to SUL distance*area of spacer)
Claims (24)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US11/438,452 US7688544B1 (en) | 2005-05-23 | 2006-05-22 | Magnetic heads disk drives and methods with floating pole tip or shunted pole tip for reduced pole tip erasure |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US68357905P | 2005-05-23 | 2005-05-23 | |
US11/438,452 US7688544B1 (en) | 2005-05-23 | 2006-05-22 | Magnetic heads disk drives and methods with floating pole tip or shunted pole tip for reduced pole tip erasure |
Publications (1)
Publication Number | Publication Date |
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US7688544B1 true US7688544B1 (en) | 2010-03-30 |
Family
ID=37452717
Family Applications (2)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US11/438,452 Expired - Fee Related US7688544B1 (en) | 2005-05-23 | 2006-05-22 | Magnetic heads disk drives and methods with floating pole tip or shunted pole tip for reduced pole tip erasure |
US11/438,820 Abandoned US20060279423A1 (en) | 2005-05-23 | 2006-05-23 | Stand alone surveillance system |
Family Applications After (1)
Application Number | Title | Priority Date | Filing Date |
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US11/438,820 Abandoned US20060279423A1 (en) | 2005-05-23 | 2006-05-23 | Stand alone surveillance system |
Country Status (3)
Country | Link |
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US (2) | US7688544B1 (en) |
CA (1) | CA2653304A1 (en) |
WO (1) | WO2006127657A2 (en) |
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US8144426B2 (en) * | 2007-05-08 | 2012-03-27 | Samsung Electronics Co., Ltd. | Perpendicular magnetic recording head having front and back poles of different specific resistances |
US20090284874A1 (en) * | 2008-05-19 | 2009-11-19 | Seagate Technology Llc | Self-aligned perpendicular writer pole and front shield |
US8089724B2 (en) * | 2008-05-19 | 2012-01-03 | Seagate Technology Llc | Self-aligned perpendicular writer pole and front shield |
US8670210B2 (en) * | 2009-11-03 | 2014-03-11 | International Business Machines Corporation | Magnetic writer having multiple gaps with more uniform magnetic fields across the gaps |
US20130120872A1 (en) * | 2009-11-03 | 2013-05-16 | International Business Machines Corporation | Magnetic writer having multiple gaps with more uniform magnetic fields across the gaps |
US9257137B2 (en) | 2009-11-03 | 2016-02-09 | International Business Machines Corporation | Magnetic writer having multiple gaps with more uniform magnetic fields across the gaps |
US9601134B2 (en) | 2009-11-03 | 2017-03-21 | International Business Machines Corporation | Magnetic writer having multiple gaps with more uniform magnetic fields across the gaps |
US8977834B2 (en) | 2011-02-14 | 2015-03-10 | Seagate Technology Llc | Dynamic storage regions |
US8832409B2 (en) | 2011-03-09 | 2014-09-09 | Seagate Technology Llc | Dynamic guarding of a storage media |
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US9042052B1 (en) | 2014-06-23 | 2015-05-26 | Western Digital (Fremont), Llc | Magnetic writer having a partially shunted coil |
US20230062839A1 (en) * | 2021-08-25 | 2023-03-02 | Kabushiki Kaisha Toshiba | Magnetic head and magnetic recording device |
Also Published As
Publication number | Publication date |
---|---|
WO2006127657A2 (en) | 2006-11-30 |
US20060279423A1 (en) | 2006-12-14 |
WO2006127657A3 (en) | 2007-09-13 |
CA2653304A1 (en) | 2006-11-30 |
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